Railroad terminals comprising rail yards receive a description, referred to as a “manifest consist”, for trains arriving at the yard. The description includes the number of cars, location of the cars, and the cargo identification for each car. The rail yards want to verify and confirm that the content of the train is as it was described. It is important for rail yard accuracy, productivity, efficiency, and thru-put that the exact position of each rail car and load is known. The train can consist of over 100 cars of various lengths. The cars can have single containers, double stacked containers, twin twenty foot containers, or a combination thereof. The rail yards typically read rail car IDs to confirm the cars' arrival in the yard. Differences in car position can result from whether the train is pushed or pulled into the yard. Further, the relaxation or tightness of the rail car couplers combined with the number of cars and car lengths can mean that car position, and therefore the loads, may be off by many feet from a theoretical position.
Modern terminals use a terminal operating system (TOS) that exercises supervisory control over terminal operations in accordance with operator commands and terminal protocols. Use of a TOS permits a terminal to keep track of inventory and schedule tasks. The TOS, working in conjunction with a PDS (Position Detection System), can automate many tasks that at one time were undertaken manually, such as loading or unloading of a car, assembly or disassembly of cars to or from a train, or the like. A TOS can only accomplish these functions with knowledge of the precise location and identification of the car and contents thereof.
In order to enable the rail yard to identify the location of rail cars effectively, the rail yard can be equipped with a GPS positioning system that includes a GPS base station and GPS receiver(s) on the cranes used to load and unload railcars, and the GPS data may be referenced to a map of the yard that is geo-referenced and converted to local coordinates for ease of use. The local coordinate system is established to match and integrate with the TOS requirements. The locomotive positioning the rail cars is equipped with a GPS antenna and rover to provide approximate location information as well as providing locations for safety protection. While GPS is one system that provides the accuracies required for location, this system alone cannot support all of the capabilities that would be desirable in profiling the cars of the train.